update lbuild to play nicely with the new CVS layout

b_cmobd_merge should not be used for any further development or testing!

cMD_PRE_CMD_SMASH are the relevant tags.

The pre-smashing contents of HEAD will be committed by yury into b_cmd as a
merge of the two branches.  These will be stabilized on b_cmd and eventually
landed onto HEAD.

- re-add cvs datestamp functionality (enabled by default), but allow it to be overridden by using the --disable-datestamp flag

- ignore errors

- chaos kernel only needs half of the old inode-max-readahead patch, so added a new patch just for chaos-2.4.18
- updated series file for chaos-2.4.18
- updated tinderbox info for chaos-2.4.18
- lbuild: removed '-D' option to cvs which was tanking builds on most clusters, cascading check for rpmbuild and rpm as the method to make rpms

- use different delimiter for CONFIGURE_FLAGS replacement, so that backslashes in the variable don't make it lose it's mind

typo fix to have lbuild error on building rpms
removed erroneous EXTRA_VERSION manipulation

b=2516